Oligosaccharides having an N-acetyllactosamine (LacNAc) structure as their skeleton and derivatives thereof play an important physiological role in vivo as a sugar chain having ability to bind to selectin family compounds. It has been revealed that expression of these sugar chains on cell surfaces participates in specific adhesion between heterogeneous cells, and function activators or inhibitors utilizing these sugar chains are expected to provide useful drugs. That is, sialyl Lewis X (SLe.sup.x), which is a representative compound, and analogues thereof are considered to be useful for alleviating various diseases accompanied with inflammation by blocking selectin molecules to inhibit the adhesion of lymphocytes to endothelial cells. Further, these sugar chains are considered to participate in adhesion of cancer cells to endothelial cells when the cancer cells undergo blood circulatory metastasis or adhesion of microorganisms to target cells when the microorganisms infect to the target cells, and therefore attached importance as a raw material for developing drugs for suppressing these diseases.
The oligosaccharides having an N-acetyllactosamine structure as their skeleton and derivatives thereof are expected to play an important role in the development of novel drugs and in the research of physiological activity in vivo. If there is obtained an N-acetyllactosamine oligosaccharide, which is their basic skeleton, in particular a long chain N-acetyllactosamine oligosaccharide similar to natural-occurring ligand sugar chains of selectin family, it is considered possible to synthesize the ligand sugar chains of selectin family, which occurs in a trace amount in a natural state, by adding properly a sialic acid residue, a fucosyl residue, a sulfate group, ceramide or the like to the N-acetyllactosamine oligosaccharide.
Further, stable supply of N-acetyllactosamine oligosaccharides, in particular long chain N-acetyllactosamine oligosaccharides, is desired. However, oligosaccharides that have N-acetyllactosamine structure as their skeleton exist only in a trace amount in a natural state and it is very difficult to synthesize long chain N-acetyllactosamine oligosaccharides so that a method for producing N-acetyllactosamine oligosaccharides on an industrial scale and at low costs is desired.
Also, sulfated N-acetyllactosamine oligosaccharides, in particular long chain sulfated N-acetyllactosamine oligosaccharides, are useful as intermediates for the synthesis of N-acetyllactosamine oligosaccharides, in particular long chain N-acetyllactosamine oligosaccharides and, hence, it is expected that provision of a method for producing such oligosaccharides will lead to stable supply of N-acetyllactosamine oligosaccharides.